Current Third Generation Partnership Projects networks, or 3GPP, provide general timing mechanisms when handling calls or messages (e.g., INVITE and non-INVITE messages) between nodes of the networks. For example, a typical 3GPP network, such as a Voice Over LTE network, or VoLTE, governs all calls using standard overarching timers, such as SIP (Session Initiation Protocol) Timer B, which is set at a maximum time within which a sender node will wait for an INVITE message to be acknowledged by a recipient node.
Another timer is Timer F, which sets the time a sender node will wait for a non-INVITE message (REFER, BYE, CANCEL, and so on) to be acknowledged by a recipient node of the network. These timers are typically set at 64 times T1 (which is the time it takes an IP packet to make a round trip between nodes, or 500 milliseconds), or 32 seconds.